Electronic circuit structure and method of fabricating electronic circuit structure having magnetoresistance element with improved electrical contacts

ABSTRACT

An apparatus including a magnetoresistance element having conductive contacts disposed between the magnetoresistance element and a semiconductor substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional application and claims thebenefit of and priority to U.S. patent application Ser. No. 16/280,199,filed Feb. 20, 2019, which is incorporated herein by reference in itsentirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

FIELD OF THE INVENTION

This invention relates generally to electronic circuit structures andmethods of fabricating electronic circuit structures having amagnetoresistance element, and, more particularly, to electronic circuitstructures and method of fabricating electronic circuit structureshaving a magnetoresistance element with improved electrical contacts.

BACKGROUND

As used herein, the term “magnetic field sensing element” is used todescribe a variety of electronic elements that can sense a magneticfield. One such magnetic field sensing element is a magnetoresistance(MR) element. The magnetoresistance element has a resistance thatchanges in relation to a magnetic field experienced by themagnetoresistance element.

As is known, there are different types of magnetoresistance elements,for example, a semiconductor magnetoresistance element such as IndiumAntimonide (InSb), a giant magnetoresistance (GMR) element, ananisotropic magnetoresistance element (AMR), and a tunnelingmagnetoresistance (TMR) element, also called a magnetic tunnel junction(MTJ) element.

Of these magnetoresistance elements, the GMR and the TMR elementsoperate with spin electronics (i.e., electron spins) where theresistance is related to the magnetic orientation of different magneticlayers separated by nonmagnetic layers. In spin valve configurations,the resistance is related to an angular direction of a magnetization ina so-called “free-layer” relative to a so-called “reference layer.”

GMR and TMR elements are known to have a relatively high sensitivity,compared, for example, to Hall effect elements. Thus, a current sensorthat uses GMR or TMR elements can sense smaller currents than can acurrent sensor that uses Hall effect elements.

TMR elements are known to have a higher sensitivity than GMR elements,but at the expense of higher noise at low frequencies.

Magnetoresistance elements are formed as a plurality of specializedlayers disposed over a surface of a semiconductor substrate, and inparticular, over an oxide or protection layer over a semiconductorsubstrate. Under the oxide layer can be various semiconductingelectronic structures, e.g., transistors, which can be diffused downwardinto the semiconductor substrate.

Referring to FIGS. 1A-1G, conventional manufacturing steps are generallyshown that can result in the conventional magnetoresistance element ofFIG. 1G.

Represented in FIG. 1A, a substrate layer 100 (here shown to be only atop layer, e.g., an oxide layer, wherein semiconductor material is belowthe substrate layer 100) has first and second conductive vias 102 a, 102b. The conductive vias can be plugged with a metal, e.g., W (tungsten).In other embodiments, the conductive vias can be coated with a metal,for example, Cu. The first and second conductive vias 102 a, 102 b canbe two individual conductive vias or two groups of conductive vias.

The substrate layer 100 has a surface 100 a. The substrate layer 100 canbe comprised of an insulating material, e.g., SiO2, under whichsemiconductor structures may be formed by diffusion techniques or thelike.

The surface 100 a can be polished, for example, by a CMP(chemical-mechanical polishing or chemical-mechanical planarization)polishing technique. A roughness of the surface can be approximately 0.3nm (RMS value of surface irregularities) after the polishing. However,top portions of the conductive vias 102 a, 102 b can have undesirablyhigher surface roughness, even after the CMP polishing. The undesirableroughness can degrade some characteristics of a magnetoresistanceelement stack disposed thereupon.

The conductive vias 102 a, 102 b can extend through the substrate layer100 down to the semiconductor structures beneath.

A stack of magnetoresistance element layers 104 used to form amagnetoresistance element (once patterned) can be formed over thesurface 100 a and in electrical communication with the conductive vias102 a, 102 b.

Represented in FIG. 1B, a hard layer 106 of hard mask material, e.g., anoxide material, e.g., SiO2, can be formed over the stack ofmagnetoresistance element layers 104, e.g., by a vapor depositiontechnique.

Represented in FIG. 1C, a patterned photoresist feature 108 can beformed over the hard layer 106, e.g., by a photolithography technique.

Represented in FIG. 1D, the hard layer 106 can be etched in a pattern ofthe patterned photoresist feature 108, e.g., by a refractive ion etch(RIE) technique. In some embodiments, this etch can be a timed etch suchthat the layer 104 is not etched. In other embodiments, this etch can bea selective etch, wherein the layer 104 is covered, for example, withSiN, such that the layer 104 is not etched.

Represented in FIG. 1E, the patterned photoresist feature 108 can beremoved, e.g., with a standard chemical process.

Represented in FIG. 1F, the stack of magnetoresistance element layers104 can be etched in a pattern of the hard layer 106. The pattern canbe, from a top view (not shown), a yoke shape, round shape, rectangularshape, or other shape. For this etch, an ion beam etch (IBE) can beused, which is suitable for etching of the different materials of thestack of magnetoresistance element layers 104. The same etch processreduces a thickness of the hard layer 106.

Represented in FIG. 1G, a cap layer 110 can be applied by depositionprocess to protect the resulting magnetoresistance element 104 havingthe shape. The cap layer can be comprised of, for example, SiN,

It should be apparent that electrical connections are made between thestack of magnetoresistance element layers 104 and semiconductorstructures under the substrate layer 100 by way of only the conductivevias 102 a, 102 b. For these conventional arrangements, there is noother material between the stack of magnetoresistance element layers 104and the conductive vias 102 a, 102 b.

It is known that some magnetoresistance elements can have an undesirableoffset voltage (a resistance indicating non-zero magnetic field whenexperiencing zero magnetic field). The offset voltage can be differentunit-to-unit and can change with temperature. One contributing structureof a magnetoresistance element that can cause variability of the offsetvoltage is in variability of resistances of the conductive vias 102 a,102 b, at a junction to the magnetoresistance element 104.

The conductive vias 102 a, 102 b can also contribute to otherundesirable characteristics of a magnetoresistance element. In thisregard, a transfer characteristic between resistance and sensed magneticfield has a slope (sensitivity) that is generally, but not completely,linear within a range of external magnetic fields. Within the linearrange, the slope of the transfer characteristic can have nonlinearperturbations (e.g., steps) away from a smooth transfer characteristic.The steps can result from magnetic characteristics of magnetic domainswithin a so-called free layer in a magnetoresistance element. In turn,the characteristics of the free layer causing the steps can result fromirregularities of layers below the free layer, including surfaceirregularities (i.e., roughness) of the surface 100 a. In conventionalmagnetoresistance elements, the roughness of the surface 100 a is madeworse by presence of the conductive vias 102 a, 102 b in direct physicalconnection to the magnetoresistance element. Irregularities in thesurface 100 a of the semiconductor substrate can result in crystallineirregularities in layers of the magnetoresistance element 104 above thesurface 100 a of the semiconductor substrate, including in the freelayer.

It would be desirable to provide a magnetoresistance element andtechniques to fabricate the magnetoresistance element that can provide abetter electrical coupling to a bottom of the magnetoresistance element,which can result in a lower offset voltage of the magnetoresistanceelement, which can result in less variability of the offset voltageunit-to-unit and with respect to temperature, and which can also resultin better crystalline uniformity, with fewer defects, of themagnetoresistance element.

SUMMARY

The present invention provides a magnetoresistance element andtechniques to fabricate the magnetoresistance element that can provide abetter electrical coupling to a bottom of the magnetoresistance element,which can result in a lower offset voltage of the magnetoresistanceelement, which can result in less variability of the offset voltageunit-to-unit and with respect to temperature, and which can also resultin better crystalline uniformity, with fewer defects, of themagnetoresistance element.

In accordance with an example useful for understanding an aspect of thepresent invention, a method of fabricating an electronic circuitstructure can include one or more of: providing a semiconductorsubstrate, a top surface of the semiconductor substrate comprised of afirst layer of insulating material, the top surface of the semiconductorsubstrate comprising first and second conductive vias passing throughthe top surface of the semiconductor substrate; polishing the topsurface of the semiconductor substrate comprised of the first layer ofinsulating material; depositing a layer of conductive material over thetop surface of the substrate and in electrical contact with the firstand second conductive vias, a top surface of the conductive materialdistal from the top surface of the semiconductor substrate; etching thelayer of conductive material to generate first and second conductivecontacts having a separation parallel to the top surface of thesemiconductor substrate, wherein the first conductive contact is inelectrical contact with the first conductive via and not with the secondconductive via, and wherein the second conductive contact is inelectrical contact with the second conductive via and not with the firstconductive via; and depositing a magnetoresistance element upon thefirst and second conductive contacts, the magnetoresistance elementhaving a bottom surface in electrical contact with the first and secondconductive contacts and a top surface distal from the first and secondconductive contacts, wherein the first conductive contact is disposedbetween the first conductive via and the magnetoresistance element andthe second conductive contact is disposed between the second conductivevia and the magnetoresistance element, wherein the first and secondconductive vias are operable to pass a current from the first conductivevia to the first conductive contact, from the first conductive contactto the magnetoresistance element, through the magnetoresistance elementin a direction substantially parallel to the top surface of thesubstrate, from the magnetoresistance element into the second conductivecontact, and from the second conductive contact to the second conductivevia.

In accordance with an example useful for understanding another aspect ofthe present invention, an electronic circuit structure can include oneor more of: a semiconductor substrate, a top surface of thesemiconductor substrate comprised of a first layer of insulatingmaterial, the top surface of the semiconductor substrate comprisingfirst and second conductive vias passing through the top surface, thetop surface of the semiconductor substrate being a polished surface;first and second conductive contacts having a separation parallel to thetop surface of the semiconductor substrate, wherein the first conductivecontacts is disposed between the first conductive via and themagnetoresistance element and the second conductive contact is disposedbetween the second conductive via and the magnetoresistance element,wherein the first conductive contact is in electrical contact with thefirst conductive via and not with the second conductive via, and whereinthe second conductive contact is in electrical contact with the secondconductive via and not with the first conductive via; and amagnetoresistance element disposed upon the first and second conductivecontacts, the magnetoresistance element having a bottom surface inelectrical contact with the first and second conductive contacts and atop surface distal from the first and second conductive contacts,wherein the first and second conductive vias are operable to pass acurrent from the first conductive via to the first conductive contact,from the first conductive contact to the magnetoresistance element,through the magnetoresistance element in a direction substantiallyparallel to the top surface of the substrate, from the magnetoresistanceelement into the second conductive contact, and from the secondconductive contact to the second conductive via.

In accordance with an example useful for understanding another aspect ofthe present invention, method of fabricating an electronic circuitstructure, can include: providing a semiconductor substrate having firstand second conductive vias; creating first and second conductivecontacts in electrical contact with the first and second conductivevias; and depositing a magnetoresistance element over and in electricalcontact with the first and second conductive contacts.

In accordance with an example useful for understanding another aspect ofthe present invention, an electronic circuit structure can include: asemiconductor substrate having first and second conductive vias; firstand second conductive contacts disposed over and in electrical contactwith the first and second conductive vias; and depositing amagnetoresistance element over and in electrical contact with the firstand second conductive contacts.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the invention, as well as the invention itselfmay be more fully understood from the following detailed description ofthe drawings, in which:

FIGS. 1A-1G are block diagrams representative of fabrication steps thatcan be used to fabricate a conventional magnetoresistance element;

FIGS. 2A-2G are block diagrams representative of other fabrication stepsthat can be used to fabricate another magnetoresistance element;

FIGS. 3A-3G are block diagrams representative of other fabrication stepsthat can be used to fabricate another magnetoresistance element; and

FIGS. 4A-4D are block diagrams representative of other fabrication stepsthat can be used to fabricate another magnetoresistance element.

DETAILED DESCRIPTION

Before describing the present invention, it should be noted thatreference is sometimes made herein to GMR or TMR elements havingparticular shapes (e.g., yoke shaped or pillar shaped). One of ordinaryskill in the art will appreciate, however, that the techniques describedherein are applicable to a variety of sizes and shapes.

As used herein, the term “anisotropy” or “anisotropic” refer to amaterial that has different properties according to direction in thematerial. A magnetoresistance element can have a particular axis ordirection to which the magnetization of a ferromagnetic or ferrimagneticlayer tends to orientate when it does not experience an additional,external, magnetic field. An axial anisotropy can be created by acrystalline effect or by a shape anisotropy, both of which can allow twoequivalent directions of magnetic fields. A directional anisotropy canalso be created in an adjacent layer, for example, by anantiferromagnetic layer, which allows only a single magnetic fielddirection along a specific axis in the adjacent layer.

In view of the above, it will be understood that introduction of ananisotropy in a magnetic layer results in forcing the magnetization ofthe magnetic layer to be parallel to that anisotropy in the absence ofan external field. In the case of a GMR or TMR element, a directionalanisotropy provides an ability to obtain a coherent rotation of themagnetization in a magnetic layer in response, for example, to anexternal magnetic field, which has the property of suppressing thehysteresis behavior of the corresponding element.

As is known, there are different types of magnetoresistance elements,for example, a semiconductor magnetoresistance element such as IndiumAntimonide (InSb), a giant magnetoresistance (GMR) element, ananisotropic magnetoresistance element (AMR), and a tunnelingmagnetoresistance (TMR) element, also called a magnetic tunnel junction(MTJ) element.

As used herein, the term “magnetic field sensor” is used to describe acircuit that uses a magnetic field sensing element, generally incombination with other circuits. Magnetic field sensors are used in avariety of applications, including, but not limited to, an angle sensorthat senses an angle of a direction of a magnetic field, a currentsensor that senses a magnetic field generated by a current carried by acurrent-carrying conductor, a magnetic switch that senses the proximityof a ferromagnetic object, a rotation detector that senses passingferromagnetic articles, for example, magnetic domains of a ring magnet,and a magnetic field sensor that senses a magnetic field density of amagnetic field.

The terms “parallel” and “perpendicular” may be used in various contextsherein. It should be understood that the terms parallel andperpendicular do not require exact perpendicularity or exactparallelism, but instead it is intended that normal manufacturingtolerances apply, which tolerances depend upon the context in which theterms are used. In some instances, the term “substantially” is used tomodify the terms “parallel” or “perpendicular.” In general, use of theterms “substantially” and the term “about” reflect angles that arewithin manufacturing tolerances, for example, within +/−ten degrees.

Structures and methods described herein apply to GMR, TMR, and AMRmagnetoresistance elements, and any other types of magnetoresistanceelements. However, it should be appreciated that the same or similarstructures and methods can apply to other magnetoresistance elements,either now known or later discovered.

Referring now to FIGS. 2A-2G, manufacturing steps are generally shownthat can result in the magnetoresistance element of FIG. 2G. Stepsrecited below can be performed in other orders.

Represented in FIG. 2A, a substrate layer 200 (here shown to be only atop layer, e.g., an oxide layer, wherein the semiconductor material isbelow the substrate layer 200) has conductive vias 202 a, 202 b. In someembodiments, the conductive vias can be plugged with a metal, e.g., W(Tungsten). In other embodiments, the conductive vias can be coated witha metal, for example, Cu. The conductive vias 202 a, 202 b can be twoindividual conductive vias or two groups of plugged vias.

The substrate layer 200 has a surface 200 a. The substrate layer 200 acan be comprised of a nonconducting material, e.g., SiO2, under whichsemiconductor structures may be formed by diffusion techniques or thelike.

The surface 200 a can be polished, for example, by a CMP(chemical-mechanical polishing or chemical-mechanical planarization)polishing technique. A roughness of the surface can be approximately 0.3nm (RMS value of surface irregularities) after the polishing. However,top portions of the conductive vias 202 a, 202 b can have undesirablyhigher surface roughness, even after the CMP polishing.

The conductive vias 202 a, 202 b can extend through the substrate layer200 down to the semiconductor structures beneath.

A conductive layer 204 can be formed over the surface 200 a and inelectrical communication with the conductive vias. The conductive layer204 can be comprised of a metal, e.g., TiN. The conductive layer 204 canbe formed, for example, by a sputtering technique.

It will become apparent from discussion below, that a magnetoresistanceelement is in contact with the conductive layer, and is not in directcontact with the conductive vias 202 a, 202 b.

In some embodiments, a top surface 204 c of the conductive layer 204 canbe polished, for example, with a CMP process. However, it is describedin conjunction with FIG. 2F below that polishing of the conductive layer204 can be performed at a later step.

Patterned photoresist features 206 a, 206 b can be formed over theconductive layer 204, for example, with a photolithography process.

Represented in FIG. 2B, the conductive layer 204 can be etched to formfirst and second conductive layer portions 204 a, 204 b. A chemical etchcan be used. The first conductive layer portion 204 a can beelectrically coupled to the conductive vias 202 a and the secondconductive layer portion 204 b can be electrically coupled to theconductive vias 202 a. The first conductive layer portion 204 a is notdirectly electrically coupled to the second conductive layer portion 204b.

Represented in FIG. 2C, the patterned photoresist features 206 a, 206 bcan be removed, e.g., by a standard chemical process.

Represented in FIG. 2D, an insulator layer 208 can be formed over thesurface 200 a of the substrate layer 200, and over and between the firstand second conductive layer portions 204 a, 204 b. The insulator layer208, for example, can be comprised of SiO2 and formed by a vapordeposition technique.

Represented in FIG. 2E, the insulator layer 208 can be etched down to alevel still above the surface 200 a. This etching can be achieved, forexample, by a refractive ion etch (ME) technique.

Represented in FIG. 2F, the insulator layer 208 and the first and secondconductive layer portions 206 a, 206 b can be polished and planarized,for example, using a CMP technique. The CMP technique can result in atop surface of the insulator layer 208 and top surfaces of the first andsecond conductive layer portions 204 a, 204 b having a surface roughnessof about 5 nm.

For this arrangement, the polishing of the conductive layer 204described above in conjunction with FIG. 2A can be omitted, since theconductive layer 204 is polished here as represented in FIG. 2F.

In some alternate embodiments, the etch represented in FIG. 2E and theplanarization represented in FIG. 2F can be reversed in order such thatthe polishing precedes the etch. In these embodiments, the polishingdoes not expose or polish top surfaces of the first and secondconductive layer portions 206 a, 206 b, and exposure is achieved withthe following etch. For these embodiments, the conductive surface 208 ispolished at an earlier step, for example, as described above inconjunction with FIG. 2A.

Represented in FIG. 2G, a stack of magnetoresistance element layers 210can be deposited over the insulator layer 208 and over the first andsecond conductive layer portions 204 a, 204 b.

After deposition, the stack of magnetoresistance element layers 210 canbe etched in a pattern to form a magnetoresistance element. Patterningof the stack of magnetoresistance element layers 210 can be performedwith techniques described above in conjunction with FIGS. 1E-1G. Thepattern can be, from a top view (not shown), a yoke shape, round shape,rectangular shape, or another shape. For this etch, an ion beam etch(IBE) can be used.

A cap layer (not shown) similar to the cap layer 110 of FIG. 1G can beapplied by deposition process to protect the resulting magnetoresistanceelement 210 having the shape. The cap layer can be comprised of, forexample, SiN.

It should be apparent that electrical connections are made between themagnetoresistance element and semiconductor structures under thesubstrate layer 200 by way of the conductive vias 202 a, 202 b and byway of the first and second conductive layer portions 204 a, 204 b.

Top surfaces of the first and second conductive layer portions 204 a,204 b can be smoother than is the top surface 200 a of the substratelayer 200, particularly proximate to the conductive vias 202 a, 202 b.Thus, irregularities in crystal structure of layers of themagnetoresistance element 210 are reduced. Also, resistances through theconductive vias 202 a, 202 b, through the first and second conductivelayer portions 204 a, 204 b, to the magnetoresistance element 210 can beless than resistances through the conductive vias 102 a, 102 b to themagnetoresistance element 104 of FIG. 1G, resulting in a lower offsetvoltage and less variation of the offset voltage unit-to-unit and withrespect to temperature.

Referring now to FIGS. 3A-3G, manufacturing steps are generally shownthat can result in the magnetoresistance element of FIG. 3G. Stepsrecited below can be performed in other orders.

Represented in FIG. 3A, a substrate layer 300 (here shown to be only atop layer, e.g., an oxide layer, wherein the semiconductor material isbelow the substrate layer 300) has conductive vias 302 a, 302 b. In someembodiments, the conductive vias can be plugged with a metal, e.g., W(Tungsten) In other embodiments, the conductive vias can be coated witha metal, for example, Cu. The conductive vias 202 a, 202 b can be twoindividual conductive vias or two groups of plugged vias.

The substrate layer 300 has a surface 300 a. The substrate layer can becomprised of, an insulating material, e.g., SiO2, under whichsemiconductor structures may be formed by diffusion techniques or thelike. The surface 300 a can be polished, for example, by a CMP(chemical-mechanical polishing or chemical-mechanical planarization)polishing technique. A roughness of the surface can be approximately 0.3nm (RMS value of surface irregularities) after the polishing. However,top portions of the conductive vias 302 a, 302 b can have undesirablyhigher surface roughness, even after the CMP polishing.

The conductive vias 302 a, 302 b can extend through the substrate layer300 down to the semiconductor structures beneath.

A conductive layer 304 can be formed over the surface 300 a and inelectrical communication with the conductive vias. The conductive layer304 can be comprised of a metal, e.g., TiN. The conductive layer can beformed, for example, by a sputtering technique.

The conductive layer 304 can be polished and planarized, for example,with a CMP technique.

A hard layer 306 can be formed over the conductive layer 304. The hardlayer can be comprised of an insulating material, e.g., SiO2, forexample, by a vapor deposition technique.

Represented in FIG. 3B, patterned photoresist features 308 a, 308 b canbe formed over the hard layer 306, for example, with a photolithographyprocess.

Represented in FIG. 3C, the hard layer 306 can be etched to form firstand second hard layer portions 306 a, 306 b. The etching can beperformed, for example, with a reactive ion etch (RIE) technique, achemical etch, resulting in sharp edges of the etched features.

Represented in FIG. 3D, the patterned photoresist feature 308 a, 308 bcan be removed, for example, by a chemical process.

Represented in FIG. 3E, the conductive layer 304 can be etched to formfirst and second conductive layer portion 304 a, 304 b. The firstconductive layer portion 304 a can be electrically coupled to theconductive vias 302 a and the second conductive layer portion 304 b canbe electrically coupled to the conductive vias 302 a. The firstconductive layer portion 304 a is not directly electrically coupled tothe second conductive layer portion 304 b.

Edges 304 aa, 304 ba can be sloped to an angle of less than about sixtydegrees relative to the surface 300 a of the substrate layer 300. Toachieve the slope, in some embodiments, an ion beam etching (IBE)process can be used. However, to achieve the slope, other physicaletching techniques, as opposed to chemical etching techniques, can beused.

Represented in FIG. 3F, the first and second hard layer portions 306 a,306 b can be removed by etching. This etching can be achieved, forexample, by a refractive ion etch (ME) technique.

Represented in FIG. 3G, a stack of magnetoresistance element layers 308can be deposited over the first and second conductive layer portions 304a, 304 b, including over the sloped edges 304 aa, 304 ba of theconductive layer portions 304 a, 304 b.

After deposition, the stack of magnetoresistance element layers 308 canbe etched in a pattern. Patterning of the stack of magnetoresistanceelement layers 308 can be performed with techniques described above inconjunction with FIGS. 1E-1G. The pattern can be, from a top view (notshown), a yoke shape, round shape, rectangular shape, or other shape.For this etch, an ion beam etch (IBE) can be used.

A cap layer (not shown) similar to the cap layer 110 of FIG. 1G can beapplied by deposition process to protect the resulting magnetoresistanceelement 308 having the shape. The cap layer can be comprised of, forexample, SiN.

It should be apparent that electrical connections are made between themagnetoresistance element and semiconductor structures under thesubstrate layer 300 by way of the conductive vias 302 a, 302 b and byway of the first and second conductive layer portions 304 a, 304 b.

Top surfaces of the first and second conductive layer portions 304 a,304 b, including the edges 304 aa, 304 ba, can be smoother than is thetop surface 300 a of the substrate layer 300, particularly proximate tothe conductive vias 302 a, 302 b. Thus, irregularities in crystalstructure of layers of the magnetoresistance element 308 are reduced.Also, resistances through the conductive vias 302 a, 302 b, through thefirst and second conductive layer portions 304 a, 304 b, to themagnetoresistance element 308 can be less than resistances through theconductive vias 102 a, 102 b to the magnetoresistance element 104 ofFIG. 1G, resulting in a lower offset voltage and less variation of theoffset voltage unit-to-unit and with respect to temperature.

Referring now to FIGS. 4A-4D, manufacturing steps are generally shownthat can result in the magnetoresistance element of FIG. 4D. Stepsrecited below can be performed in other orders.

Represented in FIG. 4A, a substrate layer 400 (here shown to be only atop layer, e.g., an oxide layer, the semiconductor would otherwise bebelow the substrate layer 400) has conductive vias 402 a, 402 b,conductive with a metal, e.g., SiO2 or SiN. The conductive vias 402 a,402 b can be two individual conductive vias or two groups of conductivevias.

The substrate layer 400 has a surface 400 a and can be comprised of aninsulating material, e.g., SiO2, under which semiconductor structuresmay be formed by diffusion techniques or the like. The surface 400 a canbe polished, for example, by a CMP (chemical-mechanical polishing orchemical-mechanical planarization) polishing technique. A roughness ofthe surface can be approximately 0.3 nm (RMS value of surfaceirregularities) after the polishing. However, top portions of theconductive vias 402 a, 402 b can have undesirably higher surfaceroughness, even after the CMP polishing.

The conductive vias 402 a, 402 b can extend through the substrate layer400 down to the semiconductor structures beneath.

A conductive layer 404 can be formed over the surface 400 a and inelectrical communication with the conductive vias. The conductive layer404 can be comprised of a metal, e.g., TiN. The conductive layer can beformed, for example, by a sputtering technique.

The conductive layer 404 can be polished and planarized, for example,with a CMP technique.

Patterned photoresist features 406 a, 406 b can be formed over theconductive layer 404, for example, with a photolithography process.

Represented in FIG. 4B, the conductive layer 404 can be etched to formfirst and second conductive layer portion 404 a, 404 b. The firstconductive layer portion 404 a can be electrically coupled to theconductive vias 402 a and the second conductive layer portion 404 b canbe electrically coupled to the conductive vias 402 a. The firstconductive layer portion 404 a is not directly electrically coupled tothe second conductive layer portion 404 b.

Edges 404 aa, 404 ba can be sloped to an angle of less than about sixtydegrees relative to the surface 400 a of the substrate layer 400. Toachieve the slope, an ion beam etching (IBE) process can be used.However, other physical etching techniques, as opposed to chemicaletching techniques, can also be used.

Represented in FIG. 4C, the patterned photoresist features 406 a, 406 bcan be removed by a chemical process.

Represented in FIG. 4D, a stack of magnetoresistance element layers 408can be deposited over the first and second conductive layer portions 404a, 404 b, including over the sloped edges 404 aa, 404 ba.

After deposition, the stack of magnetoresistance element layers 408 canbe etched in a pattern. Patterning of the stack of magnetoresistanceelement layers 408 can be performed with techniques described above inconjunction with FIGS. 1E-1G. The pattern can be, from a top view (notshown), a yoke shape, round shape, rectangular shape, or other shape.For this etch, an ion beam etch (IBE) can be used.

A cap layer (not shown) similar to the cap layer 110 of FIG. 1G can beapplied by deposition process to protect the resulting magnetoresistanceelement 408 having the shape. The cap layer can be comprised of, forexample, SiN.

It should be apparent that electrical connections are made between themagnetoresistance element and semiconductor structures under thesubstrate layer 400 by way of the conductive vias 402 a, 402 b and byway of the first and second conductive layer portions 404 a, 404 b.

Top surfaces of the first and second conductive layer portions 404 a,404 b, including the edges 404 aa, 404 ba, can be smoother than is thetop surface 400 a of the substrate layer 400, particularly proximate tothe conductive vias 402 a, 402 b. Thus, irregularities in crystalstructure of layers of the magnetoresistance element 408 are reduced.Also, resistances through the conductive vias 402 a, 402 b, through thefirst and second conductive layer portions 404 a, 404 b, to themagnetoresistance element 408 can be less than resistances through theconductive vias 102 a, 102 b to the magnetoresistance element 104 ofFIG. 1G, resulting in a lower offset voltage and less variation of theoffset voltage unit-to-unit and with respect to temperature.

All references cited herein are hereby incorporated herein by referencein their entirety.

Having described preferred embodiments, which serve to illustratevarious concepts, structures and techniques, which are the subject ofthis patent, it will now become apparent that other embodimentsincorporating these concepts, structures and techniques may be used.Accordingly, it is submitted that the scope of the patent should not belimited to the described embodiments but rather should be limited onlyby the spirit and scope of the following claims.

Elements of embodiments described herein may be combined to form otherembodiments not specifically set forth above. Various elements, whichare described in the context of a single embodiment, may also beprovided separately or in any suitable subcombination. Other embodimentsnot specifically described herein are also within the scope of thefollowing claims.

What is claimed is:
 1. An electronic circuit structure, comprising: asemiconductor substrate, a top surface of the semiconductor substratecomprising a first layer of insulating material, the top surface of thesemiconductor substrate comprising first and second conductive viaspassing through the top surface, the top surface of the semiconductorsubstrate being a polished surface; and first and second conductivecontacts having a separation parallel to the top surface of thesemiconductor substrate, wherein the first conductive contact isdisposed between the first conductive via and a magnetoresistanceelement and the second conductive contact is disposed between the secondconductive via and the magnetoresistance element, wherein the firstconductive contact is in electrical contact with the first conductivevia and not with the second conductive via, and wherein the secondconductive contact is in electrical contact with the second conductivevia and not with the first conductive via, wherein the magnetoresistanceelement is disposed upon the first and second conductive contacts, themagnetoresistance element having a bottom surface in electrical contactwith the first and second conductive contacts and a top surface distalfrom the first and second conductive contacts, wherein the first andsecond conductive vias are operable to pass a current from the firstconductive via to the first conductive contact, from the firstconductive contact to the magnetoresistance element, through themagnetoresistance element in a direction substantially parallel to thetop surface of the substrate, from the magnetoresistance element intothe second conductive contact, and from the second conductive contact tothe second conductive via.
 2. The electronic circuit structure of claim1, further comprising: an insulating material disposed between the firstand second conductive contacts.
 3. The electronic circuit structure ofclaim 1, wherein the top surfaces of the first and second conductivecontacts are exposed.
 4. The electronic circuit structure of claim 1,wherein the magnetoresistance element is deposited over the first andsecond conductive contacts and over the top surface of the second layerof insulating material.
 5. The electronic circuit structure of claim 1,wherein the top surface of the layer of conductive material is exposed.6. The electronic circuit structure of claim 1, wherein respectiveproximate edges of the first and second conductive contacts are slopedless than sixty degrees relative to the top surface of the semiconductorsubstrate.
 7. The electronic circuit structure of claim 6, wherein themagnetoresistance element is over the sloped proximate edges.
 8. Theelectronic circuit structure of claim 1, wherein the first and secondconductive contacts have respective proximate edges sloped less thansixty degrees relative to the top surface of the semiconductorsubstrate, wherein the magnetoresistance element is also disposed uponthe sloped proximate edges.
 9. An electronic circuit structure,comprising: a semiconductor substrate having first and second conductivevias; first and second conductive contacts disposed over and inelectrical contact with the first and second conductive vias; and amagnetoresistance element over and in electrical contact with the firstand second conductive contacts.
 10. The electronic circuit structure ofclaim 9, further comprising: an insulating material disposed between thefirst and second conductive contacts.
 11. The electronic circuitstructure of claim 10, wherein the first and second conductive contactshave respective proximate edges sloped less than sixty degrees relativeto a top surface of the semiconductor substrate, wherein themagnetoresistance element is disposed upon the sloped proximate edges.